Beta-cyanoethylated thiobarbituric acid

ABSTRACT

THIS INVENTION RELATES TO A B-CYANOETHYLATED THIOBARBITURIC ACID SELECTED FROM THE GROUP CONSISTING OF THOSE OF THE FORMULAE:   1-(NC-CH2-CH2-),2-(S=),5,5-DI(NC-CH2-CH2-)-HEXAHYDRO-   PYRIMIDINE-4,6-DIONE   2-(S=),5-(NC-CH2-CH2-)-HEXAHYDROPYRIMIDINE-4,6-DIONE,   1,5-DI(NC-CH2-CH2-),2-(S=)-HEXAHYDROPYRIMIDIN-4,6-DIONE   1,3,5,5-TETRA(NC-CH2-CH2-),2-(S=)-HEXAHYDROPYRIMIDIN-   4,6-DIONE   THESE COMPOUNDS ARE USED AS PRIMARY BRIGHTENERS IN NICKEL PLATING.

United States Patent 3,658,820 ,B-CYANOETHYLATED THIOBARBITURIC ACIDFrank Passal, Detroit, Mich., assignor to M & T Chemicals, Inc., NewYork, N .Y.

No Drawing. Application Apr. 17, 1967, Ser. No. 645,080, which is adivision of application Ser. No. 364,278, May 1, 1964, now Patent No.3,341,433. Divided and this application Dec. 19, 1969, Ser. No. 888,096

Int. Cl. C07d 51/24 US. Cl. 260260 1 Claim ABSTRACT OF THE DISCLOSUREThis invention relates to a B-cyanoethylated thiobarbituric acidselected from the group consisting of those of the formulae:

These com-pounds are used as primary brighteners in nickel plating.

This application is a divisional application of U .S. patent applicationSer. No. 645,080, now pending, filed Apr. 17, 1967, which in turn is adivisional application of US. patent application Ser. No. 364,278, filedMay 1, 1964, and now US. Pat. No. 3,341,433.

This invention relates to electroplating nickel and more particularly tothe electrodeposition of bright nickel.

Nickel electrodeposits as plated from Watts, high chloride, fluoborate,etc. type baths are not bright when plated in thicknesses substantiallygreater than those of very thin strike or flash coatings. Such depositsdo not increase in luster with increasing thickness but rather decreasein brightness until dull matte deposits are obtained. To obtain thickbright deposits from such baths, it is necessary to add'certainadditives, commonly of organic nature, which assist in producing highlylustrous deposits with good rate of brightening. It is a commoncharacteristic of such so-called bright nickel plating baths that thedeposits tend to increase in luster with increasing thickness. Aparticular advantage of these bright nickel? baths is that brightdeposits can be obtained on basis metals which have not been polished orwhich do not have a high starting luster, within reasonablespecification thickness of nickel. Other concomitant advantages such aslevelling or the ability of the deposits to fill in pores, scratches, orother superficial defects of the basis metal may also be obtained.

Addition agents useful as brighteners in nickel plating baths aregenerally divided into two classes on the basis of their predominantfunction. Primary brighteners are materials used in very low orrelatively low concentration typically 0.002-0.2 g./l. which bythemselves may or may not produce visible brightening action. Thoseprimary brighteners which may exhibit some brightening effects when usedalone generally also produce deleterious side effects such as reducedcathode efiiciency, poor deposit color, deposit brittleness andexfoliation, very narrow bright plate range, or failure to plate at allon the low current density areas. Secondary brighteners are materialswhich are ordinarily used in combination with primary brighteners but inappreciably higher concentration than that of the primarybrighteners-typically 1 g./l. to 30 g./1. These materials by themselves,may produce some brightening or grain refining effects, but the depositsare not usually mirror bright and the rate of brightening is usuallyinadequate.

Ideally, when primary and secondary brighteners of properly chosen andcompatible nature are combined, it 1s possible to obtain, over a widecurrent density range, ductile, levelled deposits which exhibit a goodrate of brightening. The rate of brightening and levelling may vary indegree depending on the particular cooperative additives shown and theiractual and relative concentrations. A high degree of rate of brighteningand levelling is generally desirable, particularly where maximum lusteris desired with minimum nickel thicknesses. The concentrations of thesecondary brighteners may usually vary within fairly wide limits.Theconcentrations of the primary brighteners must usually be maintainedwithin fair- 1y narrow limits in order to maintain desirable propertiesincluding good ductility, adequate coverage over low current densityareas, etc. Any bright nickel system which can be rendered more tolerantto fluctuations in primary brightener concentrations will have obviousadvantages, particularly since the low concentration of primarybrighteners and the intrinsic chemical nature of some make strictcontrol by chemical analysis diflicult. A primary brightener which canbe used over a wide range of concentration is of great value in brightnickel plating.

It is an object of this invention to provide improved nickel plate byuse of a new class of superior primary brighteners. It is a furtherobject of this invention to pro vide an eflicient process forelectrodepositing bright and smooth nickel deposits. Another object ofthis invention is to provide bath compositions for nickel plating fromwhich bright nickel electrodeposits are obtained. Other objects of thisinvention may be apparent to those skilled in the art on inspection ofthe following description.

In accordance with certain of its aspects, the process of this inventioncomprises electrodepositing nickel from an aqueous nickel electroplatingbath containing a secondary brightener and, as a primary brightener, acyanoethylated compound selected from the group consisting ofcyanoethylated thiohydantoin, cyanoethylated 2-imidazolid'ine thione',cyanoethylated thiobarbituric acid, and cyanoethylated Z-thiouracil.

The novel compounds which may be used in practice of this invention mayinclude cyanoethylated thiohydantoin, cyanoethylated 2 imidazolidinethione, cyanoethylated thiobarbituric acid, and cyanoethylated 2thiouracil. Thiohydantoin (I) may be cyanoethylated as herein disclosedto produce 4 mono-,B-cyanoethyl thiohydantoin (H), 3,4 di-,B-cyanoethylthiohydantoin (III), 3,4,4-tri- ,B-cyanoethyl thiohydantoin (IV), andl,3,4,4-tetra-B-cyanoethyl thiohydantoin (V):

H o o en; o o -h ornomoN HN NH HN NH (III) 3 OG----C(OH2CH2CN):OCC(CH2CH2CN)2 P paration of the novel compounds of this invention ma brdanc wi th 1 l1 EN MCHECHCN) (NCOHCHQN NwHzGm yti e m acco e th efolowing 1 ustrative if if s s 5 0o--o OC-C(CH2CH2CN)2 H2 H It will beapparent to those skilled in the art that each H111 11TH CN 6 ENN(CH:CH:CN)

of these compounds I-IV may each exist in tautomeric 10 equilibrium withits tautomer, e.g. for III:

11 H (I) (Iv) 0 o-d om0mom o C-- (CHzOHzCN) 1 EN N(CH2CH2CN) S N NwmomoN15 l, Q- 'HCHFCHCH (V CHr-CH Other isomers may be formed depending uponthe par- (NCEOHQQIX /N(CHZGHQCN) ticular conditions of synthesis.

It will also be apparent that mixtures of compounds, e.g. isomers, ormixtures of compounds which have been 2; cyanoethylated to a differentdegree may be simultaneous- (VII) 1y formed; and these mixtures need notbe separated for 5 utilization as hereinafter set forth, because it maybe found 40H CHCN that these mixtures perform as well as pure compoundsH NH P or pure isomers. Inertly substituted thiohydantoin derivall tivessuch as l-acetyl Z-thiohydantoin may also be cyanoethylated to producee.g. monocyanoethylated l-acetyl-Z- 0 Wm) (cmcmom thiohydantoin. Whenthe composition is such (as is the case with the compositions ofFormulae II-IV) that the (NCCHzCH9I IC1 I(CH2CH2CN) tautomerism permitsformation of the thiol from the 11 thione, then the compounds may besoluble in water or dilute alkali due to formation of the thiol salt.(IX) 2 imidizolidine thione (VI) may be cyanoethylated,

e.g. to produce 1,3-di-fl-cyanoethyl-Z-imidazolidine thione VII Similarto the cyanoethylated thiohydantoins, the CH:CH1 CH:CH: 4Ocyanoethylated Z-imidazoline thiones and Z-thiobarbitu- HN NH (NCHZCHZQNNwHzomoN) rates, in which at least one imino group remainsunsubstituted, may exist in the keto-enol tautomeric forms.

5} r H 2-thiouracil (XIII) may be cyanoethylated to produce 3 S3-mono-fl-cyanoethyl Z-thiouracil (XIV); 1, 3-d'i-B-cyano- (VII) ethylZ-thiouracil (XV); 1,3-4-tri-fl-cyanotehyl Z-thioura- '1 XVI t 2thiobarbituric acid (VIII) may be cyanoethylated to c1 e c producesimilarly designated compounds typified by 1,5 ,5-tri-fl-cyanoethyl-Z-thiobarbituric acid (IX):

(OH allow H(!3=CHC=O Ho=oH- J=0 2 I OG-CHz-CO 0O (1} O0 HN NH(NCCH2CH:)N NH HNCNH 1 1 g HNON(CH2OH2CN) H II S g s 5 (VIII) (IX) 5 5(XIII) (XIV) HC=CHC=O Other cyanoethylated thiobarbituric acidderivatives (NCCHZCHQN McmcHwN) may includeS-fl-cyanoethyl-Z-thiobarbituric acid (X), 1,5-di-B-dicyanoethyl-Z-thiobarbituric acid '(XI), and 1,3,5, gS-tetra18-cyanoethyl-Z-thiobarbitnric acid (XII): (XV) (CHzCHzCN)(CHzCHiCN) (ONCH2OH2) 0=OH-C=O 00-03-330 OOCHCO (CN0H20H)N /N(CH:CHON)HN(fiYNH HN( N oHioH2oN s s (X) (XI) (XVI) (CHaCHzCN): oo-o-oo 0(NCCH2CH2)N G N(CH2CH2CN) The reaction of the heterocyclic thiocarbonylcompound with acrylonitrile may be effected under relatively (XII) mildconditions. Preferably water may be used as a reaction medium.Preferably the reaction may be accelerated by use as catalyst of aproton acceptor such as a base such as sodium hydroxide, potassiumhydroxide, or quaternary ammonium hydroxides such as benzyl trimethylammonium hydroxide or amines such as triethylamine. v

Reaction may be effected by mixing the components preferably in thepresence of a reaction medium and preferably accompanied by vigorousagitation. To effect lower degrees of cyanoethylation, e.g. to obtainproducts having up to about three cyanoethyl groups, the acrylonitrilemay be present in the amount of 11.5 equivalent of acrylonitrile. Tointroduce four or more cyanoethyl groups, preferably the acrylonitrilemay be used in amount of at least two or more equivalents. The positionof the cyanoethyl groups may in all cases be readily confirmed byinspection of the infra-red spectrum of the compounds, by the SodiumAzide-Iodine test, elemental analysis, etc.

The temperature during the reaction may be controlled to fall in therange of C. to about 70 C. Lower temperatures e.g. 0 C.35 C. favor lowerdegrees of cyanoethylation, while higher temperatures, e.g. 35 C.- 70 C.favor higher degrees of cyanoethylation. The time of reaction, dependingon the specific compounds reacted, may be from a few minutes, e.g. 5minutes, to several hours. Commonly it may be -60 minutes. At the end ofthe reaction time, the excess of the acrylontrile may be removed bydistillation (by heating to 80 C., or higher) or by distillation undervacuum at lower temperatures.

Alkali-insoluble products, such as tetracyanoethylated 2-thiohydantoin,will precipitate on removal of the excess unreacted acrylonitrile.Alkali-soluble products may be recovered by acidification with e.g.dilute sulfuric acid. In either case, the product may then be removed byfiltration or decantation depending on whether it is crystalline orliquid. Further purification of crystalline product may be byrecrystallization from aqueous solutions or organic solvents or mixturesthereof. Purification of liquid products may be effected by fractionaldistillation, solvent extraction etc.

Preparation of the novel compounds of this invention may be illustratedby the following specific examples:

EMMPLE 1 3,4-di-,8-cyanoethyl-Z-thiohydantoin 125 g. water, 18 g. C.P.sodium hydroxide pellets, and 50 g. 2-thiohydantoin were mixed togetherand stirred magnetically. To the solution, there was added ml. ofacrylonitrile, drop by drop, over 25 minutes (starting temperature 35C., final temperature 58 C.) Stirring was continued for another minutes.The pH after cooling to room temperature was adjusted to 5.5 with dilutesulfuric acid (1:1 by volume) and a heavy crystalline precipitateformed. The product 'was filtered off, Washed with water, and air-dried(50.0 grams)M.P. 192194 C. (Fisher-Johns). The product gave a positiveSodium Azide-Iodine test indicating presence of the enol form of thethiocarbonylgroup. The product on recrystallization from water gave M.P.195196 C. (capillary tube method).

Elemental analysis-Found (percent): C, 48.88; H, 4.55; N, 25.12 S,14.28. Calculated (percent): C, 48.63;

EXAMPLE 2 H, 4.54; N, 25.21; S, 14.42.

3,4,4-tri-B-cyanoethyl-2-thiohydant0in 50 g. 2-thiohydantoin, 150 g. ofa water solution containing 18 g. sodium hydroxide were mixed togetherand magnetically stirred. 175 ml. acrylonitrile was added, drop by drop,over a period of 1 hour. The starting temperature was 32 C. It rose to amaximum temperature of 58 C. after which it was cooled. Finaltemperature was C. Stirring was continued for 2.5 hours. The

reaction mixture was then diluted to 500 ml. with water and the pHadjusted to 7.0 with dilute sulfuric acid (1:1 by volume). A heavy oilylayer settled out. The supernatant solution was decanted off and some ofthe oil recrystallized from methanolM.P. 178183 C. (Fisher- Johns). Tothe balance of the oil, 500 ml. of methanol were added and a crystallineprecipitate formed which was filtered off, washed with methanol, andair-dried. Product recovered weighed 41.2 g. On recrystallization fromwater several times M.P. 190192 C. (capillary tube method).

Elementary analysis.Found (percent): C, 52.56; H, 4.83; N, 25.64; S,11.43. Calculated (percent): C, 52.34; H, 4.76; N, 25.44; S, 11.64.

EXAMPLE 3 1,3,4,4-tetracyanoethyl-2-thiohydantoin 5 gramstricyanoethylated 2-thiohydantoin (MP. of pure material 190-192 C.) 25g. water, 2 ml. Triton B, (benzyl, trimethyl ammonium hydroxide) and 25ml. acrylonitrile were mixed and magnetically stirred. Startingtemperature was 25 C. The mixture was heated slowly. The temperatureafter 1 hours was 72 C. Heating was continued for 30 minutes to C. Thereaction mixture was then cooled in a refrigerator. An oil separated outwhich was separated from the upper aqueous layer. The aqueous layer wasthen extracted with chloroform and the chloroform extract combined withthe oil. The mixture was aspirated on steam bath under vacuum. Theresidue was a light-yellow oil, 7.30 grams in weight. On acidificationin water, there was obtained a white crystalline precipitate which onrecrystallization from water gave M.P. 107 C. (capillary tube method). Anegative Sodium Azide-Iodine test indicated that both imino ('NH)hydrogens were substituted by the it-cyanoethyl group.

Elemental analysis.--Found (percent): C, 55.15; H, 4.66; N, 25.37; S,9.22. Calculated (percent): C, 55.03; H, 4.62; N, 25.67; S, 9.79.

EXAMPLE 4 10 g. of Z-imidazolidine thione, 25 g. water, 4 g. sodiumhydroxide, and 25 ml. acrylonitrile were mixed and stirred at roomtemperature. The temperature rose within 2 minutes to 90 C. Stirring wasinterrupted and reaction mixtue cooled to room temperature. The oilwhich was formed gave a crystalline precipitate on stirring at roomtemperature. The precipitate was filtered, water washed, ether washed,and dried in a vacuum desiccator. The product gave a negative test withsodium azide-iodine reagent indicating that the two hydrogen atomsattached to the nitrogen atoms had been cyanoethylated. The product onrecrystallization from water had a M.P. of C.- 128 C. (Fisher-Johns).Yield was 5.3 grams (26.1%) of recrystallized product. The infra-redspectra showed presence of the thiocarbonyl group.

Elemental analysis.-Found (percent): C, 52.33; H, 5.84; N, 26.73; S,15.45. Calculated (percent): C, 52.00; H, 5.77; N, 27.00; S, 15.40.

EXAMPLE 5 Cyanoethylation of 2-thiobarbituric acid 10 g. of2-thiobarbituric acid, 40 ml. water, 5 g. sodium hydroxide, and 50 ml.acrylonitrile were mixed and stirred at room temperature. The heat ofreaction rapidly raised the temperature to 50 C. and the reactionmixture was then slowly heated to 80 C. over 40 minutes. The reactionmixture was cooled to room temperature, acidified with sulfuric acid toa litmus end point, and then placed under vacuum to volatilize anyunreacted acrylonitrile. The residue was extracted with two 20 ml.portions of chloroform, the extracts combined and evaporated undervacuum on a steam bath to obtain 8.70 g. of oily residue. This residuegave a positive test with sodium azide-iodine reagent. Boiling point-200 C.

7 EXAMPLE 6 Cyanoethylation of 2-thiouracil To 75 ml. of water and 25grams 2-thiouracil there were added, while stirring magnetically, 25 ml.of an aqueous solution of NaOH containing 15 grams of NaOI-I. Thesolution was cooled to 23 C. and while stirring there were added 50 ml.acrylonitrile, drop by drop, over a period of 15 minutes, at the end ofwhich time the temperature was 24 C. The solution was then heated slowlyover a period of 25 minutes to a final temperature of 50 C. Thecolorless reaction mixture was then placed under vacuum for minutes toremove any residual unreacted acrylonitrile. To the solution there werethen added 25 ml. of a 1:1 solution by volume of concentrated H 80 andwater. The heavy, white crystalline precipitate which was formed wasfiltered off, washed with water and air dried. The weight of the productwas 46.8 g. and the M.P. 225-230 C. A positive Sodium Azide-Iodine testindicated the presence of a thiol or thione group.

Typical compounds which may be etfective as primary brighteners in thenovel nickel plating process of this invention, may include:

TABLE I (A) Dicyanoethylated 2-thiohydantoin (Example 1) (B)Tricyanoethylated 2-thiohydantoin (Example 2) (C) Tetracyanoethylated2-thiohydantoin (Example 3) (D) Cyanoethylated Z-imidazolidine thione(Example 4) (E) Cyanoethylated 2-thiobarbituric acid (Example 5) (F)Cyanoethylated 2-thiouracil (Example 6) The novel class of primarybrighteners of this invention when used in combination with suitablesecondary brighteners may give highly lustrous, brilliant depositscharacterized by high rate of brightening and levelling, excellentreceptivity for chromium plating, excellent low? current densitycoverage, and relatively very low rates of consumption. It is possibleto attain excellent ductility by control of concentration of the primarybrightener as noted infra. The baths may be used with air agitation ormechanical agitation. The baths may be electrolyzed for relatively longperiods without buildup of harmful decomposition products. Thebrighteners of this invention are also compatible with many secondarybrighteners including those characterized by low cost e.g. benzenesulfonamide.

The primary brighteners of this invention may be used in concentrationsof 0.002 g./l. to 0.050 g./l., the particcular concentration chosendepending on: the particular types and concentrations of secondary andsecondary auxiliary brighteners used, and also on such factors as theconcentrations of nickel sulfate, nickel chloride, and boric acid;operating conditions with respect to temperature and degree ofagitation; degree of luster, rate of brightening and levelling desired;and the finish of the basis metal. It is preferred to use between 0.004g./l. and 0.020 g./l.

Preferably baths containing the novel primary brighteners may operate atpH of 3-4.5 with 3.5-4.2 preferred. All pH values herein areelectrometric.

Secondary brighteners (typically present in amount of 1-4 g./l. andpreferably 2-3 g./l.) which are useful with the primary brighteners ofthis invention may include aromatic sulfonates, sulfonamides, andsulfimides, or derivatives thereof such as orthobenzoic sulfimide(saccharin), benzene sulfonamide, m-benzene disulfonamide,o-sulfobenzaldehyde, and N,N-bis(phenylsulfonyl)-4,4'- diphenyldisulfonamide, and dibenzene sulfonamide.

It is a particular feature of the primary brighteners of this inventionthat it is not necessary to use, in cooperation with secondarybrighteners, auxiliary secondary brighteners such as olefinic oracetylenic aliphatic sulfonates, which may be necessary for optimumresults when using some prior art primary brighteners.

Typical baths and processes for electroplating bright nickel includethose described in Principles of Electroplating and Electroforming, Blumand Hogaboom, pages 362-381, Revised Third edition, 1949', McGraw-HillBook Co., Inc., New York; and in Modern Electroplating, edited by A. G.Gray, The Electrochemical Society, 1953, pages 299-355. The control andoperating conditions, including the concentration of the bathingredients, pH, temperature, cathode current density, etc., of theseconventional baths are generally applicable to the present invention.Practically all baths for electroplating bright nickel contain nickelsulfate; a chloride, usually nickel chloride; a buffering agent, usuallyboric acid; and a wetting agent, e.g. sodium lauryl sulfate, sodiumlauryl ether sulfate, sodium 7-ethyl-2-methyl-4-undecanol sulfate, orsodium dihexyl sulfosuccinate. Such baths include the Well-known Wattsbath and the high chloride bath. Other baths maycontain, as the sourceof the nickel, a combination of nickel fluoborate with nickel sulfateand nickel chloride, or a combination of nickel fluoborate with nickelchloride. Typical Watts-type baths and high chloride baths are noted inTables II and III.

TABLE II Watts-type baths Nickel sulfate: 200 g./l. to 400 g./l.

Nickel chloride: 30 g./l. to g./l.

Boric acid: 30 g./l. to 50 g./l.

Temperature: 38 C. to 65 C.

Agitation: Mechanical and/ or air, pumping etc. pH 3 to 4.5electrometric TABLE III High chloride baths Nickel chloride: g./l. to300 g./l.

Nickel sulfate: 40 g./'l. to 150 g. /l.

Boric acid: 30 g./l. to 50 g./l.

Temperature: 38 C. to 65 C.

Agitation: Mechanical and/or air, pumping, etc. pH 3 to 4.5electrometric Best plating results are usually achieved in theelectrodedeposition process when there is used a method of preventingthe thin film immediately adjacent to the cathode from becoming depletedin cation content. This is desirably accomplished by agitation, such asby air agitation, solution pumping, moving cathode rod, etc. Withincreasing agitation a lower concentration of primary brightener mayadvantageously be used.

For the purpose of giving those skilled in the art a betterunderstanding of the invention, illustrative examples are hereinafterset forth. In each of the examples, an aqueous acidic nickel-containingbath was made up with the specified components. Electrodeposition ofnickel was carried out by passing electric current through an electriccircuit comprising a nickel anode and a sheet metal cathode, bothimmersed in the bath. The baths were agitated, usually by a movingcathode. Bright electrodeposits were obtained in all the tests includedherein as examples.

In Examples 7-21, the following standard bath was used as a standardsolution:

G./l. Nickel sulfate 300 Nickel chloride 60 Boric acid 45 Sodium dihexylsulfosuccinate 0.10

The primary brightener is identified from Table I supra. In Tables IVand V, the current density (CD) is expressed in ASD, amperes per squaredecimeter and the pH is the electrometric pH.

TABLE IV Ex. Amount, N Additives g./l. CD pH C.

Saccharin 2 7 "{Primary Brightener A. 0.016 4 4 55 5 8 {Saccharin 2 4 455 Primary Brightener B 0. 016

Saccharin 2 4 4 55 Primary Brightener C 0. 016 Sacchan'n 2 4 4 55'{Primary Brightener D. 0. 016 11 Saecharin 2 4 4 55 1Q "{PrimaryBrightener E 0. 016 Saceharin 0.3 12 Benzene sulfonamide.-. 2. 0 4 4 55Primary Brightener F 0. 032 13 Benzene sulfonamide 2 4 4 55 ""{PrimaryBrightener A- 0. 016 14 Benzene sulionamide 2 4 4 55 "{PrimaryBrightener B 0. 016 15 15 Benzene sulfonamide 2 4 4 55 "{PrimarysulfonamidC 0. 016 16 BenzeneBrightenere 2 4 4 55 {Primary Brightener D.0. 016 17 Benzene sulionamide 2 4 4 55 "{Primary Brightener E- 0. 016

Saccharin 0. 3 1 Benzene sulfonamide.-- 2 5 3. 5 55 Primary Brightener A0. 012 N,Nbis-phenylsulfonyl-4,4- 2 19 diphenyl disulionamide. 4 3. 5 50Primary Brightener C 0. 008 20 Dibenzene sulfonamide... 3 5 3 7 55Primary Brightener G 0. 008

o-Sulfobenzaldehyde (Na salt) 2 21 Saccharin 0. 3 4 3. 5 50 PrimaryBrightener C 0. 008

In Examples 22-26 the following standard bath was used as a standardsolution:

Nickel chloride 250 Nickel sulfate 45 Bone acid 45 Sodium dihexylsulfosuccinate 0.10

TABLE V Ex. Amount, No. Additives g./1. pH C.

Benzene sulfonamide 2 22 Saccharin 0.3 4 4 55 Primary Brig ener A- 0.008 Benzene sulionamide... 2 2d Saccharin 0.3 4 4 55 Primary Brightener0. 008 Benzene sulionamide 2 24 %aecharin1- fi 0 4 4 55 rimary rig eneBenzene sulionamide 2 25 Saccharin 0. 3 4 4 Primary Brightener D. 0.008Benzene sufonamide- 2 26 Saccharin 0. 3 4 4 55 Primary Brightener E0.008

Because of the exceptionally good low current density coverage obtainedwith the primary brighteners of this invention, they may be particularlyuseful in plating deeply recessed articles. They have a very hightolerance to metallic contaminants such as zinc and copper, and cantherefore be used in plating zinc-base die-castings which are a problemto plate using many prior art nickel brighteners because of theirsensitivity to these metals as contaminants particularly in low currentdensity recessed areas.

The nickel electrodeposits obtained from baths utilizing the novelbrightener combination are advantageous in that mirror-bright lustrouselectrodeposits having a high degree of ductility are obtained over awide range of cathode current densities. The bright nickelelectrodeposits are preferably plated on a copper or copper alloy basismetal. However, they may be electrodeposited directly on such metals asiron, steel, etc.

Although this invention has been illustrated by reference to specificexamples, numerous changes and modifications thereof which clearly fallwithin the scope of the invention will be apparent to those skilled inthe art.

I claim:

1. A fi-cyanoethylated thiobarbituric acid selected from the groupconsisting of those of the formulae:

References Cited UNITED STATES PATENTS 3,299,066 1/1967 Papesch 260-260ALEX MAZEL, Primary Examiner A. M. T. TIGHE, Assistant Examiner

